Section 605 — Underdrains, Sheet Drains, and Pavement Edge Drains

PAVEMENT EDGE DRAINS

Description

605.01This work consists of providing and installing underdrains, sheet drains, and pavement edge drains.

Material

605.02Conform to the following Section and Subsections: Aluminum-alloy corrugated pipe 707.03 Asphalt-coated pipe 707.04 Geocomposite drain 714.02 Geotextile 714.01 Metallic -coated corrugated steel pipe 707.02 Perforated concrete pipe 706.03 Plastic pipe 708 Sand 703.14 Soil and soil- aggregate materials 704.01 Underdrain backfill 703.03

Construction Requirements

605.03General. Elevate and protect sheets, panels, or rolls of geotextile filter and geocomposite with a waterproof and ultraviolet resistant cover if stored outdoors. Limit geotextile filter and geocomposite exposure to less than 10 days if using for a permanent installation. Use the same material and coating on contiguous drain sections, extensions, elbows, branch connections, and other special sections. Drain material, size, and approximate location are shown in the plans. Determine the final location and length in the field. Do not install drain material until the CO has accepted the final location and length. Excavate and backfill according to Section 209. If geotextile filter or geocomposite is used, smooth the trench surfaces by removing projections that may damage the geotext ile filter or geocomposite. Replace geotextile filter or geocomposite damaged during installation. Do not allow soil or other foreign material to enter the drain systems. Plug the highest end of installations. Provide nonperforated pipe for outlet pipe. Install outlet pipe according to Section 602. Immediately place and secure a screen made of 0.055 -inch diameter galvanized wire having approximately ½ - by ½ -inch mesh openings over the outlet ends of exposed pipes and weep holes.

605.04Placing Underdrain. Join pipe sections securely with coupling fittings or bands. Join PVC and acrylonitrile -butadiene- styrene (ABS) pipe using either a flexible elastomeric seal or solvent cement. Join polyethylene pipe with snap-on, screw -on, or wrap around coupling bands according to the manufacturer’s recommendations. Backfill and compact trenches within the limits of the roadbed according to Section 209, except use underdrain backfill. Trenches for geocomposite underdrains within the limits of the roadbed may also be backfilled with sand and compacted. If underdrain is placed in ditch lines, prevent infiltration of surface water by placing material conforming to AASHTO M 145, classification A -4, A-5, A-6, or A-7 in the top 12 inches of the trench.

(a)Standard underdrain. Place the long dimension of the geotextile filter parallel to the centerline of the trench. Position the geotextile filter, without stretching, in contact with the trench surface. Overlap the joints at least 24 inches with the upstream geotextile filter placed over the downstream geotextile filter. Place collector pipe with the perforations facing downward. Place underdrain backfill to a height of 12 inches above t he top of the collector pipe and compact. Do not displace the collector pipe. Place and compact the remainder of the underdrain backfill according to Section 209. Fold the geotextile filter over the top of the underdrain backfill with a minimum overlap of 12 inches.

(b)Geocomposite underdrain. Extend the geotextile filter from the bottom of the drainage core around the collector pipe. Construct splices and install outlet fittings according to the manufacturer’s recommendations. Prevent infiltration of soil into the geocomposite core. Place the assembled geocomposite in the trench with the face of the geocomposite against the inflow side of the trench. If the trench wall is irregular, smooth the trench wall or place a lift of underdrain backfill between the geocomposite and the trench wall. Temporarily support the drain against the trench wall while backfilling. If the trench is less than 18 inches wide, backfill the trench using sand. Backfilling and compacting in lifts are not r equired. Compact the sand by vibrating or tamping with a mechanical tamper. If the trench is at least 18 inches wide, place underdrain backfill or sand to a height of 12 inches above the top of the collector pipe and compact. Place and compact the remainde r of the underdrain backfill or sand according to Section 209.

605.05Placing Geocomposite Sheet Drain System. Do not place sheet drains against a mortar course less than 4 days old. If a geocomposite is used in conjunction with a waterproof membrane, install drainage panels compatible with the membrane according to the membrane manufacturer’ s recommendations. Assemble and place the geocomposite drain against the surface to be backfilled according to the manufacturer’s reco mmendations. Splice geocomposite drains so the flow across the edges is continuous. Overlap the geotextile filter at least 3 inches in the direction of water flow. For vertical splices, overlap the geotextile filter in the direction backfill proceeds. Connect the drainage core to the collector pipe or weep holes so the flow is continuous through the system. Extend the geotextile filter from the bottom of the drainage core around the collector pipe. Backfill with structural backfill and compact according to Subsections 209.09 and 209.10.

605.06Placing Geocomposite Pavement Edge Drain. Assemble the geocomposite pavement edge drain and outlet material according to the manufacturer’s recommendat ions and place it in the trench. If the trench wall is irregular, smooth the trench wall or place a lift of sand between the geocomposite and the trench wall. Temporarily support the drain against the trench wall while backfilling. If the trench is less th an 18 inches wide, backfill the trench using sand. Backfilling and compacting in lifts are not required. Compact the sand by vibrating or tamping with a mechanical tamper. If the trench is at least 18 inches wide, place and compact underdrain backfill or s and according to Section 209.

605.07Acceptance. See Table 605-1 for sampling, testing, and acceptance requirements. Material (except underdrain backfill) for underdrains, sheet drains, and edge drains will be evaluated under Subsections 106.02 and 106.03. Underdrain backfill will be evaluated under Subsections 106.02 and 106.04. Geocomposites will be evaluated under Subsections 106.02 and 106.03. Submit a production certification with each shipment of geocomposite that includes the name of the manufacturer, product name, style number, chemical composition of the core and encapsulating geotextile filaments or yarns, and other appropriate information to fully describe the geocomposite drain. Installation of underdrains, sheet drains, and edge drains will be evaluated under Subsections 106.02 and 106.04. Excavation and backfill will be evaluated under Section 209. Geotextile filter will be evaluated under Section 207. Outlet pipe will be evaluated under Section 602.

Measurement

605.08Measure the Section 605 pay items listed in the bid schedule according to Subsection 109.02 and the following as applicable: When measuring for a system, do not measure geotextile filters, geocomposites, collector pipes, backfill, and outlet pipe s that are part of the system. When measuring underdrain backfill and sand by the cubic yard, measure in place.

Payment

605.09The accepted quantities will be paid at the contract price per unit of measurement for the Section 605 pay items listed in the bid schedule. Payment will be full compensation for the work prescribed in this Section. See Subsection 109.05 . Table 605-1 Sampling, Testin g, and Acceptance Requirements

Material or

Product

(Subsection) Type of

Acceptance

(Subsection) Characteristic Category Test Methods

Specifications Sampling

Frequency Point

of

Sampling Split

Sample Reporting

Time Remarks

Source

Underdrain

backfill (703.03 ) Measured & tested for conformance (106.04 & 105) Quality − Subsection

703.031 per aggregate type & source of material Source of material Yes Before using in work Not required if using

Government

-furnished source

Production

Underdrain

backfill (703.03 ) Measured & tested for conformance (106.04) Gradation − AASHTO T 27 & T 11 1 per 600 yd3 Production output or stockpile Yes 4 hours −